Meshes aren't visible anymore in Solid Mode, only in Material Preview Mode. Can't select any of them
My reputation is not high enough to leave a comment, so I have to put my suggestion here in the answers. I will remove this if it doesn't solve your problem, so please let me know. Also, it would be helpful if you could share your blend file.
A few things that have helped me in the past:

try unchecking and checking the collections that you made in the outliner

try pressing &quot;/&quot; on your keyboard with an object selected, this will toggle/untoggle local view

check your clip start/end distance (press N, go to view tab, decrease the clip start number and/or increase the clip end number)